1. Field of the Invention
This invention relates to an intravenous catheter inserting device, more particularly to an intravenous catheter inserting device which enables a needle cannula to be retracted within a plunger cavity having a reduced pressure therein.
2. Description of the Related Art
Intravenous catheter inserting devices are generally used to administer medication fluid into or draw blood from a patient's vein. Referring to FIGS. 1 and 2, a conventional intravenous catheter inserting device 1 is shown to include a tubular needle seat 11 with a hub end 111, a needle cannula 12 secured to the hub end 111, a catheter hub 13 sleeved on the needle seat 11, and a flexible tubular catheter 14 secured to the catheter hub 13. In use, the catheter 14 and the needle cannula 12 are inserted into the patient's vein by a health care worker by piercing the patient's vein with a sharp tip of the needle cannula 12 which projects outwardly of the catheter 14. The health care worker then withdraws the needle cannula 12 from the catheter 14 with one hand and, at the same time, applies pressure to the patient's skin with the other hand, thereby leaving the catheter 14 in the patient's vein. Subsequently, a transfusion member (not shown) with medication fluid or an empty barrel is connected to the catheter hub 13 for administering the medication fluid into the patient's vein or for drawing blood. At this time, as the health care worker must place the used needle cannula 12 and the needle seat 11 on a tray (not shown) nearby, the exposed sharp tip of the used needle cannula 12 may create a danger of an accidental needle stick. Moreover, blood contamination may occur during connection of the catheter hub 13 to the transfusion member or the empty barrel.
Referring to FIG. 2, during the insertion procedure, the flow of blood into the catheter 14 through a notch 121 in the needle cannula 12 can be observed through the translucent catheter 14. However, due to the presence of the notch 121, the needle cannula 12 tends to be bent during passage of the catheter 14 into the patient's vein. In addition, the blood in the catheter 14 is not visible when the portion of the needle cannula 12 with the notch 121 is inserted into the patient's vein.